Hepatobiliary & Muscle II Flashcards
Dr. Parsley
What are the 3 main categories (causes) for hyperbilirubinemia?
pre-hepatic
hepatic
post-hepatic
What is hyperbilirubinemia - pre-hepatic?
increased production of bilirubin
What is hyperbilirubinemia - hepatic?
decreased hepatic uptake or secretion of bilirubin
What is hyperbilirubinemia - post-hepatic?
post-hepatic obstruction of bile flow (cholestasis) —> reflux of bilirubin into blood
Look at this picture on how bilirubin is produced
Where is bilirubin conjugated?
hepatocyte in the liver
Where is the red blood cell phagocytosed and breakdown of hemoglobin occurs to produce bilirubin?
macrophage
What are the products of hemoglobin? Where does this occur?
heme —> biliverdin & iron —> from biliverdin comes bilirubin
globin
red blood cell - pictures is showing the spleen specifically
Unconjugated bilirubin is transported with ______ in the blood
albumin
Conjugated bilirubin (Bc) is transported from the hepatocyte to _____
canaliculi
Elaborate on hyperbilirubinemia - pre-hepatic and why it leads to this
hemolysis: unconjugated bilirubin > conjugated
rate of bilirubin formation exceeds liver’s capacity for uptake/excretion
Elaborate on hyperbilirubinemia - hepatic and why it leads to this
decreased in liver functional mass
can’t get it out; converted to conjugated (intra-hepatic cholestasis)
functional cholestasis: conjugated greater than unconjugated: typically little to no ALP, but GGT high
Elaborate on hyperbilirubinemia - post-hepatic and why it leads to this
extra-hepatic cholestasis: conjugated greater than unconjugated
liver can conjugate but can’t excrete
How do you assess bilirubin?
total bilirubin (Bt)
direct: conjugated
indirect: unconjugated
What is decreased liver functional mass also called?
hepatic insufficiency
“liver failure” —> be careful saying
What is the confusion with a decrease in liver functional mass?
How do you assess hepatic function?
At what percentage of lost functional mass do liver products decrease?
70% - decrease is non-specific
What levels are glucose and globulins when testing for decreased functional mass?
glucose: can be elevated (low in fasting animals)
globulins: can be decreased because liver isn’t making globulins
Define a congenital PSS
portal vein hypoperfusion can result in secondary loss in functional mass
Define an acquired PSS
can be secondary to chronic liver disease / decrease in hepatic functional mass
What would you expect to be increased with a PSS?
ammonia
bile acids
= evidence of decreased hepatic functional mass
(liver filters toxins but if not? delivered directly to systemic blood)
Contrast congenital vs. acquired shunts?
Describe ammonia metabolism
produced by the GI microbes
transported to the liver
- made into urea
- goes into blood (BUN)
- excreted by the kidney
What are your differentials with hyperammonemia?
-
decrease in hepatic functional mass
> decrease uptake and conversion of NH3 to urea - PSS - NH3 bypasses the lvier
- feed additive in ruminants
- intestinal disease in horse
- unfasted sample
How do you handle ammonia?
has special handling requirements
Who makes bile acids?
hepatocytes
Trace the production and circulation of bile acids
made by hepatocytes —> delivered to intestine (via bile duct) —> absorbed by portal circulation —> liver —> re-excreted —> bile (enterohepatic circulation)
What are some differentials for increased bile acids?
- decrease in hepatic functional mass
- PSS
- cholestasis (do NOT run bile acids)
- false (physiologic elevation)
> gallbladder contraction elevates fasting bile acids
What are some differentials for decreased bile acids?
GI disease (abnormal motility or malabsorption)
What do you expect with simultaneous liver insufficiency and GI malabsorption?
can balance out
What are some species differences between small and large animals - bile acids?
What is the sequela to decreased hepatic function?
What is going on here? 8 year old FS Doberman with chronically increased ALT and AST
chronic liver injury
7 month old MI retriever presented for lethargy, poor weight gain, and now the owner has noted what they think looked like a seizure.
Which of these is most likely to cause the chemistry abnormalities?
a) Amanita mushroom toxicosis
b) Congenital PSS
c) Cholelithiasis
d) Bacterial septicemia
b) Congenital PSS
12 month MI beagle presented for PUPD and an enlarged abdomen
Acquired PSS
